It is known to provide cranes, excavators and the like with a chassis or support which can have a plurality of wheels, some of which may be driven, and outriggers with telescoping extensible members terminating in ground-engaging pads or feet, which can support the vehicle for various operations. In such systems, once the vehicle is in place for a particular task, the outriggers can be extended to lift the vehicle and raise the wheels from the ground, thereby increasing the stability of the chassis for any particular excavating or loading operation.
Such systems are used on backhoes, extensible-boom cranes and the like.
The outriggers are, of course, mounted separately from the wheels to enable them to be shifted, e.g. by hand, into any particular location for supporting the chassis with respect to the site at which work is to be performed. The wheels are usually mounted in their customary pattern for vehicles, at the four corners of a vehicle frame or chassis.
Since the telescoping members on one side or end of the vehicle can be extended to a greater or lesser degree than those on the opposite side or end of the vehicle, the vehicle can be supported horizontally on irregular, uneven, stepped or sloping surfaces.
Naturally, such systems cannot be used effectively for combined rolling and walking or climbing action, inasmuch as the outriggers are independent of the wheels and vice versa.
Climbing vehicles are also known but here too climbing and rolling action simultaneously cannot usually be effected and frequently it is necessary to use crawler principles for vehicles which are intended to be brought into play on irregular surfaces.